What is the difference between true course and magnetic course?

What is the difference between true course and magnetic course?

• A. True course relative to magnetic north; magnetic course relative to true north after applying variation.
• B. True course relative to true north; magnetic course relative to magnetic north after applying variation.
• C. They are the same after correction.
• D. They are used only for air navigation.

Answer: (B)

Two reference norths determine your courses: true north (geographic) and magnetic north. True course is the direction you’d steer relative to true north, as shown on charts that use geographic north. Magnetic course is the direction you’d steer relative to magnetic north when using a compass. The relation between them is set by magnetic variation—the angle between true north and magnetic north at your location. To get the magnetic course from the true course, apply the variation: subtract the variation if it’s east, or add it if it’s west. That’s why the correct description is that the true course is relative to true north, while the magnetic course is relative to magnetic north after applying variation. The other options either mix up which north reference is used, claim they’re the same, or state unnecessary scope of use.

Two reference norths determine your courses: true north (geographic) and magnetic north. True course is the direction you’d steer relative to true north, as shown on charts that use geographic north. Magnetic course is the direction you’d steer relative to magnetic north when using a compass. The relation between them is set by magnetic variation—the angle between true north and magnetic north at your location. To get the magnetic course from the true course, apply the variation: subtract the variation if it’s east, or add it if it’s west. That’s why the correct description is that the true course is relative to true north, while the magnetic course is relative to magnetic north after applying variation. The other options either mix up which north reference is used, claim they’re the same, or state unnecessary scope of use.